I have recently observed my WSUS server reporting that some clients (Windows Server 2008 SP2) need the update "Windows Server Manager - Windows Server Update Services (WSUS) Dynamic Installer (KB972493)." The clients to not detect that they need this update, but the WSUS server label the client as needing the update regardless.
Similar behavior for the WSUS SP1 dynamic installer was seen in the past. See the Microsoft Discussion Forum public.windows.server.updates_services --- see the thread titled "WSUS 3.0 SP1 KB948014 shows needed even though roll is not install" for details.
Regardless, here is the workaround:
On the client machine, install the WSUS30-KB972455-x86.exe or WSUS30-KB972455-x64.exe, but select the "Administrator Console only" during the install. This will install the Update Services MMC on the machine, but not enable WSUS on the client itself. After this, clients the WSUS server should no longer show the KB972493 as 'Needed.'